There have been hitherto found various preparations for masking tastes of unpleasantly tasting drugs.
For example, Japanese Patent Kokai 49-81526 discloses a method which comprises dissolving a macrolide antibiotic in an inert volatile organic solvent wherein a wall polymer selected from the group consisting of polyvinylacetal diethylaminoacetate (hereinafter referred to as "AEA"), cellulose acetate dibutylaminohydroxypropyl ether, aminoalkylmethacrylate copolymer E (trade name; Eudragit E) and ethyl cellulose and at least one selected from the group consisting of a wax, a higher fatty acid and a salt insoluble in the higher fatty acid are dissolved or dispersed; spray-drying the solution; and collecting the resulting encapsulated particles of the macrolide antibiotic.
On the other hand, EP Patent No. 37740 discloses a pharmaceutical preparation having an improved stability and content uniformity of drugs, and this preparation can be applied to mask an unpleasant taste, but has a drawback of a bad dissolution because waxes only are used for masking.
As an example of a pharmaceutical mixture for masking a taste of an unpleasantly tasting basic drug, EP Patent No. 69097 discloses that a dry powder for a pharmaceutical mixture comprising an encapsulated bad tasting drug in a form insoluble at high pH.
In addition, EP Patent No. 101418 discloses a pharmaceutical mixture preparation with controlled release of an active substance which includes masking of bad taste and stability increasing of the active substance characterized in that it contains an encapsulated active substance in combination with 40-99% of a release controlling substance, examples of which are a carbohydrate, a carbohydrate-related compound and a mixture of such compounds.
In the past, however, since an inert volatile organic solvent (e.g. methylene chloride, chloroform, cyclohexane, carbon tetrachloride, methylethylketone, acetone, methyl alcohol or isopropyl alcohol) should be used for dissolving coating agents, a drying step for removal of the solvent is required. As a result, the coating layer becomes porous, and the drying step requires a lot of time, equipment, labor, cost, etc. In addition, this step has risks such as inflammation and explosion in work, and the product might contain the residual inert volatile organic solvent which is feared to affect human health, therefore, it has a problem for safety.
In order to mask a taste of an unpleasantly tasting basic drug without using the inert volatile organic solvent, the present inventors disclose in EP. Patent No. 630233 a composition for oral administration comprising a complex formed by dispersing or dissolving the drug and a high polymer soluble in the stomach in a substance having a low melting point of 40 to 120.degree. C., a sugar-alcohol and a basic oxide.